Technical Abstract:
There is increased interest in sorghum as a human food because it is gluten-free, which is critical for those who suffer from celiac disease, and it has a high content of antioxidants. The storage of sorghum is anticipated to increase as the demand grows for sorghum as a substitute for gluten-based products. The lesser grain borer (LGB) (Rhyzopertha dominica F.) is a major economic insect pest of many stored grains, and can also infest sorghum. However, there are few studies which show the susceptibility of sorghum to the LGB and effects of insect population and resulting damage on the physicochemical properties of sorghum kernel and flour. We placed mixed-sex 1-2 week old LGB adults on 150 g of sorghum in 0.24 liter glass jars at population levels of 0, 10, 20, 40, and 80, and held these jars at 27 and 32oC, 57% relative humidity. We found significant differences (P<0.01) for main effects initial population level, temperature, and the interaction on F1 progeny, % insect-damaged kernels (IDK), and frass weight. Positive correlations were found among all main effects, and there were correlations between insect population levels and quality characteristics of milled sorghum including peak viscosity (r = 0.68), peak time (r = 0.63, P < 0.01), holding strength (r = 0.78), set back (r = 0.82) and final viscosity (r = 0.83).